铝锂合金的真空电子束焊接工艺

摘要

采用真空电子束焊工艺对1420铝锂合金进行了焊接,并对获得的接头进行抗拉强度、显微硬度等力学性能测试,并对接头的金相组织、拉伸断口进行了观察分析.结果表明,在电子束流为7mA、采用圆形扫描方式、焊接速度为1 000 mm/min的工艺条件下,获得的接头具有最佳的力学性能.接头微观分析显示,焊缝中心区组织主要为等轴状树枝晶,并在晶界和枝晶界分布着短棒状的共晶组织；进一步的接头焊缝XRD分析证实,焊缝金属基体为α-Al相,并含有二元共晶组织α+δ(AlLi),以及其它一些强化相如δ'(Al3Li),T(Al2MgLi)等.拉伸断口扫描观察表明,接头断口表面分布有大量细小的韧窝,呈明显韧性断裂特征.%The electron beam welding of 1420 Al - Li alloy was investigated. The tensile strength and microhardness of the welded joint were tested, and the joint microstructure and fracture were analyzed. Results show that the welded joint with excellent mechanical properties can be obtained with the welding parameters (electron beam current of 7 mA, welding speed of 1000 mm/min and circular scanning pattern). The joint microstructure analysis demonstrates that the weld consists of mainly equiaxed dendrite grains, and some short rod - like eutectic micro-structure was distributed in grain boundaries and branches. The XRD analysis of weld metal indicates that there is dominant α - Al phase in the matrix metal of joint, and also exists binary eutectic microstructure α + δ( AlLi). Moreover, some strengthened phases such as δ'( Al3Li) , T (Al2MgIi) have been found in the joint. The scanning observation of joint fracture shows that there are a large number of small - sized dimples on the fracture surface, and the joint obviously presents the characteristics of ductile fracture.